324 PROF. HUXLEY ON ARCTOCEBUS CALABARENSIS. [June 28, 
For the posterior upper molar is short and wide, so as to have a 
transversely elliptical crown, which has only two cusps, the posterior 
external, as well as the posterior internal cusp having disappeared. 
In addition to this, the hinder upper molar is set further out than 
the other molars, and the hinder lower molar has only four cusps. 
Fig. 4. 
Right dental series of both jaws of Perodicticus potto. 
A and C, upper ; B and D, lower jaw. 
In all the species yet mentioned, as in the Angwantibo, the last 
premolar has but a short heel, and differs considerably from the first 
molar. But in Otogale pallida, Galago sennaarensis (fig. 5), G. ma- 
holi, G. allenii, Otolicnus garnettii, and O. crassicaudatus the heel of 
the hinder premolar above and below becomes so large and cuspidate 
as to assume the form of a quadrieuspidate molar. This is particu- 
larly well seen in Galago sennaarensis (fig. 5) and G. allenit. In the 
latter species, even the second premolar acquires a great heel, so that 
the transition from canines to molars is quite insensibly graduated. 
In Galago minor, on the other hand, the third premolar is as dif- 
ferent from the first molar as in the Angwantibo. 
With regard to the other teeth, the hindermost upper molar of 
Otogale pallida is quadricuspidate, though the inner posterior cusp 
is low, as in the first and second molars. 
In the lower jaw the fifth cusp of the last molar is distinct, and 
the oblique ridges do not reach the antero-internal cusp. 
